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A U E R S & T > Chapter 90 - Subchondral cysts > Flashcards

Chapter 90 - Subchondral cysts Flashcards

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1
Q

What are subchondral cystic lesions (SCLs)?

A

SCLs are areas of reduced bone density or cyst-like lesions in equine joints.

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2
Q

Where are SCLs typically found?

A

They usually occur in the subchondral bone beneath articular cartilage in weight-bearing areas of joints.

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3
Q

What can SCLs cause in horses?

A

They can potentially cause lameness and can be challenging to treat.

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4
Q

What types of cystic lesions are included in SCLs?

A

SCLs can be uni- or multiloculated, and some may appear large in the metaphysis of long bones.

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5
Q

What are some mechanisms that lead to the development of SCLs?

A

Mechanisms include osteochondrosis, trauma, articular sepsis, and inflammation.

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6
Q

What is osteochondrosis?

A

A condition involving retained, thickened cartilage that can contribute to SCL development.

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7
Q

What is a common location for SCLs related to osteochondrosis?

A

The medial condyle of the femur.

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8
Q

How can trauma lead to SCL formation?

A

Trauma can create communication between the subchondral bone and the joint, allowing synovial fluid to induce necrosis.

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9
Q
A

Figure 90-1. (A) Radiographic view of a SCL in the MFC of the stifle joint of a 3-year-old mare. The lesion is in the center of the weight-bearing area of the condyle and is characterized by a radiolucency, well demarcated from the surrounding normal bone by a thin sclerotic rim. (B) Dorsolateral-plantaromedial oblique radiographic view of a distal tibia showing a mild radiolucent area (arrows) visible in the distal metaphysis.

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9
Q
A

Figure 90-2. (A) Dorsoproximal-palmarodistal oblique image of a distal sesamoid bone of a 4-year-old mare presented with lameness. A parasagittal fracture of the distal sesamoid bone with a wide line is visible. (B) Three months later: a large circular radiolucent zone (SCL) is visible over the fracture line.

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10
Q
A

Figure 90-3. Radiographic image of the right stifle of a 12-year-old mare presented with recurrent lameness 15 months after débridement of a large femoral SCL (white arrows). A large SCL of the medial tibial condyle (black arrows) as well as osteophytes on the proximomedial aspect of the tibia and the distal aspect of the femur are visible.

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11
Q
A

Figure 90-4. Postmortem specimen of a distal sesamoid bone showing a SCL in cross section. (a) Communication into the joint; (b) sclerotic border of the SCL; (c) the contents of the SCL consist of a mixture of fibrous tissue, fibrocartilage, and necrotic bone, and can be filled with synovial-like fluid.

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12
Q
A

Figure 90-5. View of a stifle joint of a 4-year-old Quarter Horse mare presenting with effusion of the left femoropatellar joint and a SCL in the medial femorotibial joint.

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13
Q
A

Figure 90-6. Flexed lateromedial image of the left stifle of an 11-year-old Quarter Horse, showing a large SCL in the MFC.
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14
Q
A

Figure 90-7. (A) Dorsoplantar view of the left hock of a Warmblood yearling presenting with severe lameness and effusion of the talocrural joint. Periosteal reactions are visible lateral to the fourth tarsal bone (arrow). (B) On the dorsal plane CT image, a small SCL in the fourth tarsal bone is visible (arrow).

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15
Q
A

Figure 90-8. (A) Dorsopalmar radiographic view of a SCL in the proximal aspect of P1. The SCL is located sagittally and surrounded by mild sclerosis (arrows). There is no obvious radiographic fissure formation. (B) In the dorsal CT view of the same lesion within the proximal sagittal aspect of P1, a SCL (arrow) is visible within the sagittal groove. (C) Transverse CT view of the same SCL showing a clear short incomplete fissure (black arrow) extending from the SCL (white arrow) dorsally, not penetrating the cortex.

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16
Q

What did a study find about SCLs and cartilage defects in ponies?

A

Experimental cartilage defects led to the development of subchondral cystic cavities.

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17
Q

How can inflammation contribute to SCLs?

A

Inflammatory mediators may lead to bone resorption and impaired healing.

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18
Q

What was revealed in a study of 703 SCL lesions?

A

The majority were found in the medial femoral condyle, followed by the phalanges.

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19
Q

What percentage of SCLs occur in males?

A

62%.

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20
Q

Which horse breeds are most affected by SCLs?

A

Thoroughbreds, American Quarter Horses, and Standardbreds are among the most affected.

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21
Q

Are SCLs more common in a specific age group?

A

They primarily affect younger horses.

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22
Q

What is the size range of SCLs?

A

They can range from a few millimeters to over 3 cm.

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23
Q

What is typically seen in the histology of SCLs?

A

They usually have a fibrous lining and may contain fibrous tissue and necrotic bone.

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24
What changes might occur in the cartilage overlying an SCL?
Signs of matrix degradation can be observed near the canal.
25
Do SCLs always cause lameness?
No, they may or may not be associated with lameness.
26
What factors can cause lameness associated with SCLs?
Pain from synovitis, intraosseous pressure, or intracystic pressure.
27
How can flexion tests affect lameness in horses with SCLs?
They usually exacerbate the lameness.
28
What is a typical radiographic finding of SCLs?
A dome-shaped or round-to-oval subchondral lucency with a surrounding sclerotic rim.
29
What imaging technique is superior for diagnosing SCLs?
Computed Tomography (CT).
30
What does CT reveal about SCLs that radiographs might miss?
It can detect the exact localization and communication between the SCL and adjacent cartilage.
31
Can scintigraphy be used for diagnosing SCLs?
Yes, it can identify occult lesions not visible on radiographs.
32
What is the initial nonsurgical treatment for SCLs?
Rest and the use of nonsteroidal anti-inflammatory drugs (NSAIDs).
33
What is the success rate of nonsurgical treatment for SCLs?
Success rates range from 45% to 64%.
34
What role do bisphosphonates play in treating SCLs?
They inhibit bone resorption and can be used to improve lameness.
35
What is the first approach in the surgical treatment of SCLs?
Intraarticular injection of steroids is often the first approach.
36
What was the success rate of corticosteroid injections in one study?
Lameness resolved in 67% of treated horses.
37
What does surgical treatment of SCLs typically involve?
Surgical débridement under arthroscopic or transcortical approaches.
38
What did research indicate about the spontaneous resolution of SCLs?
Some lesions may spontaneously resolve without treatment.
39
What additional diagnostic information can ultrasonography provide?
It can clarify the relationship between SCLs and the joint.
40
What are the potential side effects of bisphosphonates in horses?
Colic, mild CNS symptoms, nephrotoxicity, and bone fragility.
41
What is a potential issue with the injection of corticosteroids?
The risk of recurrence of clinical signs is high.
42
What condition can lead to the development of SCLs in horses?
Articular sepsis can also be a contributing factor.
43
How can traumatic events influence lameness onset in older horses?
They may correlate with ongoing intraarticular inflammation.
44
What can be seen on CT scans of SCLs that indicates bone communication?
Discontinuous subchondral bone and prominent channels leading away from the cyst.
45
Why might some horses with SCLs not experience lameness?
The lesions may not always induce sufficient pain or dysfunction to cause noticeable lameness.
46
What is the first step in surgical treatment for SCL?
The horse is anesthetized and positioned appropriately for surgery.
46
what is the preferred treatment for horses lame due to SCL?
Surgical treatment is the preferred choice, especially when conservative methods fail.
47
What approaches are used in the surgical treatment of SCL?
An intraarticular approach under arthroscopic supervision or a transcortical approach.
48
What did early studies use for treating SCLs, and what was the success rate?
Early studies used arthrotomy with an 82% success rate but could not replicate those results.
49
Why have arthrotomy approaches been abandoned in favor of arthroscopy?
rthroscopy reduces morbidity rates and allows for thorough débridement of SCLs.
50
How is the arthroscope introduced into the affected joint?
Using a routine technique to identify and access the lesion.
51
What signifies the presence of a SCL during surgery?
A canal communicating into the joint or a slight indentation on the articular surface.
52
What instruments are used to explore and identify the cyst?
blunt obturator or a right-angled probe is used.
53
What is done after the cyst has been identified?
Articular cartilage overlying the SCL is removed, and cyst contents are evacuated.
54
What is the concern regarding osteostixis during surgery?
It can lead to expansion of the cyst if not managed carefully.
55
What is required for accessing most distal limb SCLs?
A transcortical approach is often necessary due to limited accessibility.
56
What techniques guide the transcortical surgery?
Digital radiography, fluoroscopy, or CT guidance are used for planning and execution.
57
How should the drill direction be verified?
Through fluoroscopic control or frequent radiographic images.
57
What is the initial step in the transcortical approach?
A pilot hole is drilled through the bone into the cyst.
58
What advantage does 3D imaging provide in orthopedic surgery?
59
What grafting technique has shown minimal effectiveness in enhancing healing?
Simple débridement and packing with autogenous grafts.
60
What is mosaic arthroplasty?
It involves autologous osteochondral grafting as a treatment for SCLs.
61
What was the outcome of the clinical case series involving mosaic arthroplasty?
Most horses improved postoperatively with successful graft incorporation.
61
Which types of grafts showed better cartilage surface integrity in studies?
Equine grafts had the best performance compared to bovine, ovine, and human grafts.
62
What filling material is used for SCLs after transosseous curettage?
Tricalcium phosphate (TCP) granules.
63
When are TCP granules not recommended for use?
When there is a large communication between the cystic lesion and the joint cavity.
64
What technique has shown promise using parathyroid hormone (PTH)?
Injection of PTH1-34 in fibrin hydrogel after curettage of SCLs.
65
What is the significance of autologous chondrocyte implantation (ACI)?
ACI is considered the gold standard for repairing large cartilage lesions in humans.
66
What challenge remains with ACI in equine treatment?
Obtaining sufficient numbers of chondrocytes to fill large defect sizes.
67
What is bone morphogenetic protein-2 (BMP-2) used for?
It has osteoinductive effects and is being researched for equine osteochondral defect repair.
68
What were the results of using rhBMP-2 in horses with SCLs?
Increased bone density, decreased cyst size, and absence of lameness were observed.
69
How does the cortex screw technique benefit SCL treatment?
It promotes bone formation while preserving existing hyaline and calcified cartilage.
70
What is the success rate of the cortex screw technique in treating SCLs?
Lameness was eliminated in 15 out of 20 horses treated.
71
What anatomical location is often involved with traumatic SCLs?
The proximal aspect of P1 is the most common location.
72
What combination technique has been proposed for SCL treatment?
Transcortical débridement combined with insertion of a transcortical screw.
73
What positive results were observed with patient-side grafting?
It showed rapid bone formation and increased thickness of the subchondral plate.
73
What unique material has been used after débridement of SCLs?
Titanium spongiosa balls.
74
What property of titanium spongiosa balls contributes to their effectiveness?
High biocompatibility and a structure that promotes bone formation.
75
What type of lesions are common in the distal limb of horses?
SCLs of traumatic origin, often associated with fissure lines.
75
What procedure is followed to ensure proper placement of titanium balls?
CT or X-ray examination is performed to confirm placement before closure.
76
What factors influence treatment success with cortex screws?
The biomechanical environment of the SCL and stabilization of fissure lines.
77
How is the injection of PTH in horses conducted?
Through a needle into the surgically prepared cystic cavity.
77
What is the main goal of grafting procedures in SCL treatment?
To enhance healing and repair of the débrided lesions.
77
What other techniques have shown potential in SCL treatment?
The use of hydraulic biodegradable cement has yielded remarkable results.
78
What is the overall goal of surgical treatment for SCL in horses?
To alleviate lameness and restore normal function in affected horses.
79
What is the standard postoperative management for surgical interventions in horses?
The postoperative management is similar to any arthroscopic surgical intervention, requiring a potentially prolonged rest period before resuming normal activity.
80
How long does healing typically take for treated SCLs?
Healing is usually slow and can take several months to years, especially if only surgical débridement is performed.
81
What factors can enhance bone healing in treated lesions?
Using bone replacements and growth factors appears to enhance healing and shorten recovery time.
82
What factors influence the prognosis of SCLs?
Prognosis is influenced by age, breed, anatomical location, lesion size, presence of preexisting degenerative changes in the joint, and chosen treatment.
83
What demographic of horses has a decreased prognosis following surgery?
Older horses, horses with preexisting osteoarthritis, bilateral lesions, and horses with upright hindlimb conformation, such as Quarter Horses, have a significantly reduced prognosis.
84
Which anatomical location has sufficient data to assess prognosis based on studies?
Most studies focus on SCLs of the medial femoral condyle (MFC).
85
What percentage of young horses with MFC SCLs returned to soundness after surgical intervention?
64% of young horses became sound following surgical intervention.
86
What was the outcome for Thoroughbreds with MFC SCLs after surgical débridement?
64% of Thoroughbreds raced after treatment, compared to 77% of their siblings.
86
How does the age of horses affect their recovery rate?
Only 34% of mature horses (over 3 years) returned to soundness compared to a higher percentage of younger horses.
87
At what ages did the majority of the horses race after surgery?
28% raced as 2-year-olds, 61% as 3-year-olds, and 51% as 4-year-olds.
88
How does the width of the surface defect relate to the likelihood of racing success?
Horses with surface débridement of 15 mm or less had a 60.6% racing success rate, while those with defects of at least 15 mm had a 39.3% success rate.
89
What did researchers conclude about the cartilage surface involved in SCL treatment?
The amount of cartilage surface involved is a better predictor of success than the depth of the lesion.
90
What change in surgical technique has been suggested based on recent findings?
More emphasis is now placed on sparing the cartilage covering the SCL.
91
Why is the prognosis for bilateral lesions often worse?
Bilateral lesions may indicate more extensive or systemic issues affecting the horse’s joints, leading to poorer outcomes.
92
What kind of lesions are most commonly evaluated in studies regarding prognosis?
SCLs of the medial femoral condyle (MFC) are most commonly evaluated.
93
What is the significance of preexisting osteoarthritis in the prognosis of SCLs?
Horses with preexisting osteoarthritis tend to have a significantly decreased chance of returning to soundness after surgery.
94
How does the age of horses relate to their likelihood of achieving soundness post-surgery?
Younger horses have a higher success rate of returning to soundness compared to older horses.
95
What factor was found to be a better predictor of racing success than the depth of the lesion?
The width of the cartilage surface defect was found to be a better predictor.
96
How did the surgical outcomes differ for horses based on their siblings' success?
The outcomes for Thoroughbreds with MFC SCLs showed that siblings had a higher success rate, indicating genetic or management factors could play a role.
97
What is the potential impact of surgical technique changes on prognosis?
Adjusting techniques to spare cartilage may improve prognosis and outcomes for horses undergoing treatment for SCLs.
98
Figure 90-9. Dorsal CT view of a left fetlock of a 15-year-old Warmblood horse with acute severe lameness. There is an irregular SCL in the medial proximal aspect of P1; moreover, a channel (arrow) between the cyst and the medial cortex of P1 is visible.
99
Figure 90-10. Dorsal T2-weighted image of a right hind foot showing a high signal SCL (arrow) in the distal phalanx at the insertion of the lateral collateral ligament of the DIP joint.
100
Figure 90-11. (A) Intraoperative arthroscopic view under CO2 insufflation of a MFC showing a “Mercedes star” irregularity. (B) With the help of hypodermic needles, the optimal location for the instrument portal is identified. (C) Débridement of the cystic cavity is performed with an arthroscopic curette or a shaver. (D) Finally, all the content of the cyst has been removed, and the subchondral bone is visible
101
Figure 90-12. (A) Dorsopalmar radiographic view of a right MCP joint of a 12-year-old Warmblood presenting with acute, severe lameness. In the medial proximal aspect of the proximal phalanx an ill-defined radiolucent area is visible (arrows). (B) In the dorsal CT view of the same lesion, a SCL is visible. With the help of a commercially aiming device, the direction of the drill is planned on CT. (C) Intraoperative dorsal CT image showing the 4.5-mm drill bit entering the cystic lesion.
102
Figure 90-14. Mosaic arthroplasty. (A) SCL located in the MFC of a 5-year-old Hungarian half-bred mare, viewed through an arthrotomy. (B) Postoperative view after insertion of two differently sized osteochondral grafts taken from the medial femoral trochlea of the unaffected limb of the same horse. (C) Typical appearance of a 9-month follow-up arthroscopic view of a 6.5-mm defect created on the MFC and treated with an osteochondral graft in a 2-year-old research horse. (D) Typical appearance of an 8-month follow-up arthroscopic view of a donor site at the medial femoral trochlea. The defect is covered with uniform fibroid tissue. (
103
Figure 90-15. (A) Preoperative dorsopalmar radiographic view of a SCL in the distal articular aspect of the proximal phalanx. The cyst was curetted and filled with tricalcium phosphate granules through a transosseous approach. (B) Dorsopalmar radiographic view 2 years later. Tissue of bone density is filling the former SCL completely.
104
Figure 90-16. (A) Immediate postoperative caudocranial radiographic view of a SCL in the distal right MFC in a 2-year-old Arabian filly presenting with lameness. The cyst was débrided by arthroscopy and the cavity was filled with fibrin-based hydrogel and PTH1-34. (B) Follow-up radiographs 12 months later of the horse seen in (A). Note that bone density has increased considerably, and the SCL is hardly visible on radiographs.
105
Figure 90-17. (A) Postoperative dorsopalmar radiographic view of a SCL in the sagittal groove of the proximal phalanx of a 7-year-old mare, presenting with severe lameness. A 4.5-mm cortical screw has been inserted through the cyst in lag fashion. (B) Dorsopalmar radiographic view of a SCL in the second phalanx of a 13-year-old mare, presenting with lameness in the right hind limb, 2 months after surgery. The SCL had been treated with a cortex screw inserted in lag fashion. Two months later, the mare was sound at the trot.
106
Figure 90-18. (A) Craniocaudal radiographic view of the left cubital joint of a 19-year-old Warmblood gelding presenting with lameness, showing a large SCL in the medial epiphysis of the radius (arrows). (B) Postoperative view of the left cubital joint seen in (A). The cyst has been débrided through a transcortical approach (arrows), the cystic cavity has been filled with recombinant human bone morphogenetic protein-2, and a 4.5-mm cortical screw has been inserted through the cyst in neutral fashion. (C) Six months later the cystic lesion is almost not visible and the horse was sound at the trot.
107
Figure 90-19. (A) Dorsopalmar radiographic view of the distal MCIII depicting a cystic lesion that involved the entire medial condyle. (B) The defect was approached transcortically using an 8-mm drill bit and filled with injectable biodegradable bone cement (chronOS Inject). (C) The 12-month follow-up radiograph shows satisfactory healing of the defect. The animal was pain free at the walk and trot, despite the loss of medial joint space.
108
Figure 90-20. (A) Immediate postoperative caudocranial radiographic view of a SCL in the distal right MFC in a 3-year-old Warmblood mare presented with lameness. The cyst was débrided by arthroscopy and the cavity was filled with four titanium balls (arrows). (B) The follow-up radiograph 5 months later shows an increase of density of the cystic lesion (arrows), the mare was sound at the trot.

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